In the past, a magnetic recording medium which is prepared by dispersing ferromagnetic acicular crystal particles such as .gamma.-Fe.sub.2 O.sub.3, Co-containing magnetic iron oxide or CrO.sub.2 in a binder, and coating the thus obtained dispersion on a non-magnetic support to provide a magnetic layer has generally been used as a magnetic recording medium for audio recording, video recording and for computers (hereinafter, referred to as a magnetic tape).
However, with increased demand for high density recording on the magnetic recording medium, ferromagnetic alloy particles mainly composed of metal components such as iron, nickel or cobalt have been commonly used instead of the conventionally used ferromagnetic particles. Ferromagnetic alloy particles are very suitable as ferromagnetic particles for a magnetic recording medium which requires high density recording, because ferromagnetic alloy particles have high coercive force (Hc) and high residual magnetic flux density (Br).
High density recording on, particularly, video tape has been developed by shortening the recording wave lengths and by narrowing the width of the recording track. And with the increased demand for high density recording, a video tape using ferromagnetic alloy particles instead of the conventionally used ferromagnetic particles of iron oxide type has come to be used.
When ferromagnetic alloy particles are used, it is known that a higher density recording can be made and that the electromagnetic properties of the magnetic recording medium can be increased by smoothing a surface of the magnetic layer.
However, when a surface of the magnetic layer is made smooth, the friction coefficient of contact between the magnetic layer and a magnetic head increases, whereby the magnetic layer of the magnetic recording medium becomes damaged in a short time, or the magnetic layer tends to be peeled apart. In particular, a video tape is used in many cases under such harsh conditions that the tape is set at a still mode, and an increase of the friction coefficient of the magnetic layer leads to a shorter still life of the magnetic layer at a still mode. Accordingly, the running durability of the magnetic layer of a video tape has been required to be improved.
In order to improve running durability of a magnetic layer, it has been proposed in U.S. Pat. No. 3,833,412 to add abrasive agents (hard particles) such as, corundum, silicon carbide or chromium oxide, into the magnetic layer. In such a case, a relatively large amount of abrasive agents needs to be added to effectively improve running durability. However, the above method is not desirable, because a magnetic layer containing a large amount of abrasive agents causes heavy wear out of magnetic heads and makes it difficult to smooth the magnetic layer to improve electromagnetic properties. Further, it has been proposed in U.S. Pat. No. 3,687,725 to add lubricants, such as fatty acid, fatty acid ester or silicon oil, into a magnetic layer. Wear resistance can be improved by this method. However, until now, a satisfactory method which meets all requirements of high output, no decrease in output after running, and no generation of white powders which stain guide systems (hereinafter, referred to as a "guide stain"), has not yet been obtained.